The present invention relates to hand tools and more particularly to hand tools with extendable handles for increasing leverage.
Hand tools, such as wrenches, are known and commonly used by mechanics, the construction trade, other professionals and the common person for use around the home. The tools generally include at least one operational head, a shank, which may function as a handle, and perhaps a portion specifically designed as a handle. The longer the shank the more torque that can be applied to the nut, bolt screw or other fastener. Still, the tools are often used with tight confines that limit the overall length of the tool. This has led to the tools having lengths that range from a couple inches to several feet in length.
Some inventions have developed that provide for shanks of adjustable length. For instance, U.S. Pat. No. 2,438,633 to Condor, entitled Extensible Tool Shank, discloses an hand tool with an extendable handle with a plurality of preset lengths determining the lengths to which the tool may be adjusted. Others such as U.S. Pat. No. 2,869,410 to Prichard, entitled Reversible Ratchet Wrench with Handle Extension Means, disclose a handle that may be extended along the shank of a tool. Unfortunately, handles are made much shorter than the shank, which limits the range of extension of the tool without enlarging the handle and losing the function of the handle in terms of placement and comfort of the hand.
Still others have tried telescoping handles such as U.S. Pat. No. 4,307,634 to Gentry. Hollow handles are weak and easily bent in situations of increased torque, especially where the external diameter of the shank becomes narrow. Moreover, the shank receives concentrated pressure adjacent the operational head where the narrowest portions of the telescope are situated.
When moving parts are found in tools dirt and grime can collect in crevices interfering with normal operation. Life span of adjustable tools is often determined in terms of how long the dirt can be kept out of the crevices and how easily such dirt and grime can be removed. Few if any existing tools allow thorough cleaning of the components.
What is needed is an extendable shank that may be locked at any length throughout a range as opposed to specific lengths. Further, the shank should not be telescoping with easily bent hollow segments. The shank should be arranged in such a manner as to allow a near doubling of the length of the shaft. Desirably, the shank adjacent the operational head is solid metal adding strength where strength is needed. Further, the sleeve and shank should easily separate for easily cleaning of the components from dirt and grime. Yet, the tool should be designed to avoid unintentional separation of the components. These needs and other useful features are found in the below described invention.
A hand tool includes a shank with a proximal end joined to an operational head. The shank includes an elongated groove with corresponding ends adjacent the proximal end and a distal end of the shank. A slidable sleeve has an internal channel with the sleeve sized to receive the shank. The sleeve defines a set aperture.
A set is disposed in the set aperture and is positioned to bias into the elongated groove on the shank. The set prevents sliding between the shank and sleeve when tightened and allows sliding between the shank and the sleeve when the set is loosened.
A selective lock relates between the sleeve and the shank. The lock prevents separation of the sleeve and the shank when the sleeve and shank are in rotational alignment. The lock allows separation of the sleeve and the shank when the sleeve and shank are out of rotational alignment.
The selective lock may include a bore which houses a spring and a ball and which correspond with a snap hole. The device may include a plurality of selective locks such as a proximal selective lock and a distal selective lock.
Advantageously, this invention provides for easy separation of the sleeve and shank to allow dirt and grime to be cleaned from the components.
As a further advantage, the shank is joined to the operational head and the sleeve adjusts away from the shank, which allows the shank to be made solid, adding strength at the surgical neck of the tool.
As yet another advantage the tool is provided with selective locks holds the sleeve or handle in the fully extended position and the fully retracted position.
As yet another advantage, the tools is provided with a set that allows the sleeve to be selectively locked relative to the shank, allowing the tool to remain a fixed length until change is desired.
As still yet another advantage, the set is positioned in a groove to preclude unintentional easy separation of the sleeve from the shank.
Also advantageously, the present invention provides sufficient clearance between the sleeve and shank to avoid the need for sticky dirt collecting lubricant, yet remain small enough to avoid dirt and grime from entering the tool.
Also an advantage is when the lock screw is left loose the extension handle may be moved in and out during the tightening and loosening of a fastener in the same stroke, allowing more torque to start rotation and reduce handle length for speed and to clear handle swing in close confined spaces.
These and other advantages will be found in the description of the invention below.